1. Field of the Invention
The present invention is related to a wireless power transmission device, and more particularly, to a wireless power transmission device having feedback control.
2. Related Art
Wireless charging technology which utilizes non-contact wireless power transmission has been widely applied to mobile devices such as consumer electronics, smart phones, and tablet computers.
Please refer to FIG. 1. FIG. 1 is a diagram illustrating a prior art wireless charging module 100. The wireless charging module 100 includes a power transmitter 102, a power receiver 104, and a transmission unit 106. The transmission unit 106 utilizes inductive coils 108 and 110 as an antenna for transmitting and receiving power. A radio frequency identification (RFID) system is included in the design of the wireless charging module 100 in order that an RFID feedback signal from the power receiver 104 can be transmitted to the power transmitter 102 by utilizing the same inductive coils 108 and 110 for controlling power transfer between the power transmitter 102 and the power receiver 104.
Due to the fact that the RFID feedback signal's operating frequency is about several megahertz (MHz) and the RFID feedback signal is transmitted via the same inductive coils used to transmit power, the same inductive coils are required to transfer power and the RFID feedback signal. Thus the RFID feedback signal waveforms may be distorted by voltages induced by the power transmission on the inductive coils, thereby interfering the RFID feedback signal and causing control errors and instability of the wireless charging module 100. The higher the power transmission is, the more severe the interference becomes. As a result, applications of wireless charging technology are limited and cannot be applied to higher power transfer.